Document publishing software packages may bundle word processing, page design, graphics editing and book building functions into an integrated product for producing documents of various complexities from simple memos to complex multi-chapter documents with imported graphics. One example of such a document publishing software package is PageMaker.TM. produced by Adobe Systems Incorporated, of San Jose, Calif.
Other document preparation programs or systems provide only word processing functions and limited graphics capabilities. These type of document systems include full function word processors such as Microsoft Word produced by Microsoft Corporation, of Redmond, Wash.
Once produced, documents are often modified from their original format to conform to new or changing user requirements. For example, a document may contain a single column of text, which may have to be converted into two or more columns. In performing such a conversion, the system is required to adjust the layout of the content associated with the various pages of the document to accomplish the user selected changes. One possible effect of a change in format is that it may result in underflow or overflow conditions between pages. An underflow occurs when a layout change results in more space being available on a page to display text, and accordingly, text from a next page must be moved in order to fill the available space. An overflow condition arises when text from one page of the document spills over to another page as a result of the recasting process.
In a document publishing system, the page framework defines how content is organized and displayed on a given page of a document. The page framework includes members which are used to position, align or otherwise organize the content on the page. The members include margins, page edges, ruler guides, and column edges. Page properties such as page size and orientation (portrait or landscape) affect the location of framework members on the page. Accordingly, when modifications to a page property are made by the user, the document publishing system is required to adjust the associated framework members to their new locations. Any content associated with (or aligned to) one of these relocated frame members must be similarly relocated in the new page layout or the user will be required to manually perform the adjustment.
FIG. 1 shows a typical word processor approach to displaying content on a page. A word processor program determines the available column space in the page framework for content based on the position of framework members as based on user selected (or default) page properties of the page framework (100). The content (e.g., words typed by the user) is positioned automatically within the available column area (102). Thereafter, the page may be displayed (104). Upon receipt of a request to change the page framework (in the form of a change to a page property or the repositioning of an individual framework member) (106), the program determines the available column space for the content based on the new page framework (108). Thereafter, the program adjusts the page framework members and repositions the content within the available space (110). Finally, the new page may be displayed (112). This process repeats at step 104 each time a page framework member or page property is adjusted by the user. For example, to make the content area narrower on the page, the user is required to widen the left and/or right margins. Arbitrary positioning of content--especially multiple pieces of content such as an assortment of text and graphic objects--is impossible.
Other document publishing systems allow for more freedom in the placement of content on a page. Such systems typically treat content as objects. For example, PageMaker allows a user to place content (either text or graphics) arbitrarily on a page. The user sizes the objects and thereafter positions them on the page at arbitrary locations. This approach allows complete flexibility of layout for the page, giving such systems superiority over word processor programs for situations where design freedom is important.
While this type of freedom is desirable, difficulties arise when the page framework is altered. Typically, free form document publishing systems that allow for the arbitrary placement of content on a page are unable to recast content automatically on a page in response to a change in the page framework. Accordingly, content must be resized or repositioned manually after changes are made to the page framework. In these free form document publishing systems, alignment of content to framework members is considered entirely coincidental and no notice is taken of them by the program when acting on user instructions to modify the page framework.